the last hurdle before happy hour begins. Thank you so much to the AOSSM and to the NATA for inviting me to be part of this exchange lecture. I was asked to give an overview of the research across my career, as well as highlight some of the more recent work that I've been doing in the area of chronic ankle instability. So I'm at the University of Kentucky, and so my lab group has been affectionately called the Wildcats Ankle Research, and we're waging war on ankle instability, not only the acute ankle sprain, but also the spectrum of development of chronicity. And we look at it from two fronts. We attack from the area of prevention. We want to improve research in the area of prevention, not only preventing the ankle sprain acutely, but preventing the development of chronic ankle instability. And we also wish to attack it from the area of treatment and improving understanding of how we can treat the ankle sprain better, but also treat the ankle sprain to prevent the chronic ankle instability from happening. I also hope that my research career has brought awareness that we need to bring bigger artillery to this attack, and that we can bring better awareness that this patient population has been underrepresented in the literature. A lot of my career has been devoted to trying to help us understand better definitions of what is chronic ankle instability, at least from the conservative management patient. We can start with a simple term. We know it's a very heterogeneous description, but we at least know that they've had at least one ankle sprain, and now they're presenting to us with residual problems. I've been very proud of the work that I've been associated with the International Ankle Consortium, a group of international researchers devoted to better understanding of the consequences of ankle sprains. We produced a tripartite position statement in which the purpose was to improve the inclusion criteria for research studies using chronic ankle instability subjects to improve the quality of the literature. We had basic criteria that, in addition to having the history of an ankle sprain, we established what would be the recommended way to document how much instability in giving way that they report, as well as advocate for ankle region-specific patient-reported outcomes. We feel that over almost 10 years now, the quality of the research has improved in this particular aspect of chronic ankle instability. I'm also proud of another position statement we did a few years after that in which we wanted to bring awareness to the prevalence, the societal and financial impact, and the long-term consequences of lateral ankle sprains, and we hope that this is becoming a useful resource for both clinicians and researchers going forward. Several of my colleagues in that International Ankle Consortium over the last 20 years have produced some really strong systematic reviews that really have become evolutionary models of what is chronic ankle instability, and I think consistently across these papers and across these decades, we see that there's some combination of mechanical and sensory motor or functional insufficiencies that go into a mixture to produce models of chronic ankle instability, again, that have evolved over the last 20 years. I'm happy that some of the work that I've done has contributed to some of the systematic reviews, but we still are striving to better define this conservatively managed chronic ankle instability patient, and so what I wanna turn my attention to some of the more recent work that I've been doing to try to contribute to this understanding of the CAI model. An emerging area in trying to understand why there is residual giving way, residual injuries, we believe is pointing towards some central nervous system adaptations in this patient population, and I've taken an approach in sort of three aspects of trying to better understand and contribute to defining some of these central nervous system adaptations. The first way we did it is looking at more of a biomechanical or neuromuscular control approach, so this group of papers here is all from my lab group from my time at University of Toledo, and then more recently, University of Kentucky, and we use techniques in our laboratory such as balance assessments, gait assessments, a variety of different landing and hopping tasks, and what we found consistently across this body of work is that those with chronic ankle instability were presenting with movement pattern differences, strength deficits, muscle activation pattern changes in their knees and their hips, but not necessarily in their ankles, and these patients had no prior history of any insult to their knees or their hips, so we attributed this pattern that perhaps is a reorganization that's manifesting proximally to the ankle, and these movement patterns and neuromuscular control changes may be contributing to the ongoing instability and re-injury rates that we're seeing that are so high, but to try to further understand why those patterns are merging, we've also taken another approach to contributing to this growing evidence, and that's looking at the communication pathway. We know that control of peripheral joints requires information coming from spinal and supraspinal pathways. We want to focus on the motor cortex in terms of the supraspinal pathway, and one way we can quantify that, we have been quantifying it, is through a setup called transcranial magnetic stimulation, shown here in my lab. If you're not familiar with it, the idea is that we provide a stimulation to the cortex to elicit a response in a muscle of interest, and what we aim to see, or what we have seen, is that when there is more stimulation needed to get the same desired response in that muscle, it suggests a dampening or an alteration in that communication pathway from the cortex down to the muscle. Now, this has been pretty well established in the knee literature. You can find a host of literature that suggests that those with ACL reconstruction have a dampening of this pathway to their quadricep muscle. We were among the first, we were the first, to my knowledge, to take this model applied to chronic ankle instability patients, and what we see in this graph is that the bars on the left show that, bilaterally, it took more stimulation to the cortex to get the fibularis longus to elicit a response relative to healthy controls, suggesting, again, there was perhaps a dampening of their motor pathways. We also were interested in spinal reflexes, and this is a representation of how we might assess that using something called H-reflex assessment, in which you stimulate a peripheral nerve, here it's the tibial nerve, and again, we're looking at the fibularis longus, and you can look at both the afferent, efferent component of that stimulation, and the idea is that we can solicit a dampening response of the spinal reflexes. So, in the last 10 years, my laboratory groups and this body of work has shown consistently dampening in both spinal and supraspinal pathways. That's starting to further build the puzzle that there is some changing happening in the central nervous system that's residually there and may be contributing to the reinjury rate. The final piece that we've wanted to look at has been very recent. If there is movement pattern differences, perhaps related to communication pathway changes, is there anything structurally actually changing at the brain level that we never would have considered happening, a peripheral joint injury causing something happening structurally in the brain to change? Well, we're starting to scratch the surface that might be the case. So, what we've done is partner with brain MRI experts at UK, and we started with looking at one of the most common clinical manifestations, a balance deficiency. We know our ankle sprain patients have a balance insufficiency. So, we measured their balance, as you can see here, and also had brain scans done to look specifically at what's called white matter microstructure. It's a way to look at the integrity of specific brain tracks. In this study, we focused on the cerebellum as a known important balance control center. And the result is something called FA, or fractional anisotropy. A lower number would indicate you have more structural changes in your white matter. And we see in this data that the numbers were statistically lower in the lateral ankle sprain history group. And this final data here is just our balance indice from the force plate measures. And quickly, that number that would be lower indicates worse balance. So, what we found was that there's, as expected, a balance insufficiency. And it's simultaneously present with some changes in a balance control center in the brain. Now, why that's happening, we don't yet know. Again, this is some of our most recent work. But we're very interested in this because what does this mean? Well, as I said, CAI is a heterogeneous condition with a whole host of mechanical and functional deficiencies. In the recent years, we feel we're helping to better understand that through some of the central nervous system adaptations. And we're excited to see where that might change interventions and how it might change the way we consider rehabilitation efforts. We're in the middle of a clinical trial that I'll give you a preview that I hope maybe in a few years I can come back and share some information. But funded through the Department of Defense, we are endeavoring to latch on to some of these sensory motor insufficiencies, introduce a sensory motor focused rehab, which we're calling SMART, and then track them for a year with some of the measurements I just shared with you, such as TMS and brain MRI, hoping that we have a better outcome for this conservative management of chronic ankle instability. The last thought I'll leave you with, what is really the best treatment for ankle injury? Well, I've had the pleasure to travel internationally over the last few decades talking about ankle instability with international colleagues. One stop in particular was in Dublin. And apparently they've already figured out how to treat ankle sprains quite effectively. And then I arrived in University of Kentucky in 2014. We have our own native spirit, and I would say that that's also quite successful. So I'm anxious to hear what maybe some of your field research has yielded, and maybe we can collaborate in the future. So with that, thank you very much. Thank you.

chronic ankle instability

prevention

treatment

biomechanical control

neuromuscular control